Everything on the dash works as it should, such as the speeddometer, tach, etc., except the odometer. I tried to locate information about it in the manual, and did a brief search on this forum, but found nothing specific about the manner in which it is connected. Is it via cable, wire, or ?

Where does it connect...on the transmission, transfer case or ?.

 

If there's a problem with a sensor, (ie vehicle speed sensor) the PCM/BCM would set a DTC in memory and most likely turn on the SES light. Data is sent to both of the instrument cluster logic modules by means of class II communication from the PCM and BCM. Could be a problem with one of the instrument cluster logic modules or the trip/odometer module, all 3 are inside the instrument cluster. There are companies that refurbish instrument clusters. You send them yours, they either refurbish yours, or send you another one.

 

I had to Google to understand all of your acronyms, but I'm still not certain that the picture is clear for me. For the purpose of clarity, I don't care what this signal is sent through, I want to know how it originates?

Obviously it must start at the power-train somewhere, but does it start from an electronic sensor, a gear driven cable or what? It rather sounds as though you implied that the sensor is purely electronic and processed by the PCM/BCM before arriving at the speedometer...true?

Since the SES light is not lit, that seems to rule out the possibility that you described, but then I will allow for a variation of what you said. In any case, I'm not inclined to rip out the entire instrument panel and ship it off, without a better understanding than I now have. Is not the speedometer a unit that can be separated from the rest of the panel?

 

The VSS is located in the tail housing of the transmission on 2WD, and in the side of the transfer case on 4WD. It is a gear driven electronic sensor that sends data in the form of PPM to the PCM. The PCM uses the data for several different calculations including vehicle speed, transmission shift points, ABS, etc etc. The PCM and BCM are connected via a network and data is shared from various sensors by both modules for different vehicle functions. The data is sent through one wire called classII communications where ever it needs to go, ie the instrument cluster logic module for indicating vehicle speed and distance travelled.

There are several components in the instrument cluster that all use the same classII communication wire. If trip and odometer are the only functions that don't work, the problem is either in the logic module, which is soldered to a printed circuit board, or the trip/odometer module, which is also soldered to the printed circuit board. The entire cluster is serviced as a unit, not individual components in the cluster. To accurately diagnose the entire cluster, a TechII scan tool is necessary, they usually run upwards of $10K. Some of the less expensive, ($5K) scan tools can access certain components in the cluster.

VSS - Vehicle Speed Sensor
PCM - Powertrain Control Module
BCM - Body Control Module
DTC - Diagnostic Trouble Code
PPM - Pulses Per Mile
ABS - Antilock Brake System

 

Thanks, I think that I can now grasp what you are saying. At least I can rule out what I originally thought, because since both the speedometer and odometer are run by the same signal, and the speedometer does work, it is obvious that the signal is being sent from the transfer case (4WD).

I really don't need the odometer (except for insurance purposes, since my rate is based on mileage), so with the expense of this repair, I will have to put it on the back burner for a while.

 

Yes, the speedometer and trip/odometer signals both originate from the VSS.